Transistors and Diodes

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Raytheon CK718 & CK722

Released in 1953, the blue painted Raytheon CK722 PNP transistor is quite possibly the most famous and beloved transistor ever made. Initially made in a clear plastic painted package, the CK722 was part of a family of parts originally derived from the CK718 hearing aid transistor. Early transistor production was a slapdash affair at best, and many of the CK718's that Raytheon produced did not meet the advertised specifications. These low-bin parts were packaged under a different part number, CK722, and sold as low performance devices specifically for the hobby market. As a result, an entire generation of electronics enthusiasts cut their teeth on blue painted CK722 transistors. The CK722 became so iconic that Raytheon began to paint their other semiconductors in the same shade of blue to capitalize on the popularity of the device.

Raytheon CK718 & CK722 Transistors
Raytheon CK782

The CK782, made by Raytheon, is a germanium PNP transistor intended for use in early hearing aids. First released sometime around 1955, the early CK782's make use of Raytheon's iconic blue paint job, popularized by the hobbyist friendly CK722 shown above. The CK782 is quite tiny for a metal can transistor, rivaling the size of later devices in TO-92 plastic enclosures.

Raytheon CK782 Transistor
Sylvania 2N35

The Sylvania 2N35 is an early consumer-grade germanium transistor, notable for its NPN construction at a time when most of the available devices were of PNP construction. Released in 1953, the 2N35 was a competitor to the popular Raytheon CK722. Like many early transistors, the 2N35 is packaged in a small elliptical metal can, which can mate to common transistor sockets of the era.


Sylvania 2N35 Transistor
General Electric 2N43

The 2N43, along with the 2N44 and 2N45, were General Electric's first commercially produced alloy junction transistors. First produced in 1953, the 2N43 used a vacuum-sealed glass and metal package designed by Conrad Zierdt, a General Electric production engineer. This packaging, which abandoned the failure-prone epoxy and potting compounds of other early transistors, significantly lowered electrical variation between devices. A variant of this transistor, the 2N43A, was the first transistor to be qualified for use by the USAF.


General Electric 2N43 Transistor (2N43A)
Siemens TF65

The TF65 is a germanium junction transistor that introduced in 1957. This transistor was made in both a silver and black cased version; the black version is shown here. This model of transistor is best known for it's use inside Kundo's line of electromagnetic pendulum clocks, which make use of the transistor in the pendulum drive circuit. The TF65 is a common point of failure in these clocks, requiring replacement with a more readily available germanium part number, the AC125 being the most common choice.

Siemens TF65 Transistor
Mullard ORP61

The ORP61, manufactured by Mullard, is a cadmium sulfide photocell in a tiny tubular package. The clear case of this device mimics the shape of many earlier transistors manufactured in Europe and Great Britain, a fact which causes many collectors to mistakenly identify this part as a diode or transistor. The strange internal construction of the ORP61 does little to help in identification; this part lacks the typical serpentine pattern of the average photo-resistor, instead a translucent block is bonded across two leads at the head of the device. The ORP61 has a nominal resistance of 60kOhms and a maximum power rating of 70 mW at 350 volts DC.

Mullard ORP61 Photocell
Raytheon CK2000

If a steampunk fetishist was tasked with building an old-timey analog to an optoisolator, a raysistor might be the result. Raysistors are primitive optical isolation components that contain an incandescent bulb and a CDS photoresistor closely coupled in a blob of clear epoxy. The example shown here, a CK2000 manufactured by Raytheon, has had it's metal cover removed so the internal structure can be seen. Raysistors have one immediately obvious disadvantage over optoisolators... incandescent lamps can and do burn out. For this reason the CK2000 is designed to be a user replaceable part, and mates with a special four-pin socket that was provided in the same packaging.

Raytheon also produced much longer lasting raysistors that utilized a neon bulb instead of an incandescent lamp as the light source. This eliminated the threat of a burned out lamp filament, but resulted in a part with much more limited analog capabilities.


Raytheon CK2000 Raysistor
Philco 1N82

The 1N82 is a mid-1950s era germanium diode intended as a low loss mixer for use in television receivers. The 1N82 has a classic 'cat whisker' point contact, which can be seen pressing against the diode's square germanium crystal through the glass housing. Unlike some earlier devices, no provision has been included for manual adjustment of the point contact's position after installation of the diode in it's target system.


Philco 1N82 Transistor
Honeywell H5

The Honeywell H5 is an early power transistor which was released in 1956. The H5 is a germanium PNP device with a power rating of 10 watts, and is the first Honeywell power transistor to use hook lugs instead of flying leads. Honeywell originally developed this series of transistors for use in aircraft fuel systems; some versions had power dissipation ratings in excess of 50 watts.


Honeywell H5 Transistor
Honeywell H10

The Honeywell H10, first released in 1957, is a successor to the 1965-era H5 power transistor. The H10 is a large metal-can device with hook leads and a threaded lug for heatsink or chassis mounting. This transistor has a power rating of 15 amps, and was packaged in a case almost twice the diameter of the earlier H5. The example shown here is a undefined later variant, marked with the part number H10A1XOC.


Honeywell H10 Transistor
General Electric 2N188

The 2N188 is a relatively unremarkable early PNP transistor manufactured by General Electric. The 2N188 was intended to be used as a medium power audio frequency amplifier, and has fairly linear gain and output. This transistor is packaged in a top-hat package; earlier versions included a top nipple for evacuation, which was dropped in later revisions.

General Electric 2N188 Transistor

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